This disclosure provides a printer pen having a pressure regulation system and a mechanism for purging air from the pen using the pressure regulation system. More specifically, a pressure sensor and a permanent magnet actuator open and close an internal valve to selectively pressurize a local ink container with ink to achieve a precise pen back pressure, which may be specific for each pen in order to maximize print quality. The pen also has a blow-off vent and internal conduits which channel trapped air upward, toward the vent. When too much air is detected within the ink container (based on transient response as sensed by the pressure sensor), the pen is moved near an external tab at or near a service station, such that the tab physically opens the blow-off vent. The internal valve is also opened to permit the pen to pressurize (ink is normally at below-atmospheric pressure) and thereby expel air through the blow-off vent. Once sufficient air is released, the pen is moved to close the blow-off vent and, with the internal valve closed, the print head is fired a controlled amount to achieve optimal back pressure.